/* * resource.c * * Read uncompressed and compressed metadata and file resources. * * Copyright (C) 2010 Carl Thijssen * Copyright (C) 2012 Eric Biggers * * wimlib - Library for working with WIM files * * This library is free software; you can redistribute it and/or modify it under * the terms of the GNU Lesser General Public License as published by the Free * Software Foundation; either version 2.1 of the License, or (at your option) any * later version. * * This library is distributed in the hope that it will be useful, but WITHOUT ANY * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A * PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public License along * with this library; if not, write to the Free Software Foundation, Inc., 59 * Temple Place, Suite 330, Boston, MA 02111-1307 USA */ #include "wimlib_internal.h" #include "io.h" #include "lzx.h" #include "xpress.h" #include "dentry.h" #include #include /* * Reads all or part of a compressed resource into an in-memory buffer. * * @fp: The FILE* for the WIM file. * @resource_compressed_size: The compressed size of the resource. * @resource_uncompressed_size: The uncompressed size of the resource. * @resource_offset: The offset of the start of the resource from * the start of the stream @fp. * @resource_ctype: The compression type of the resource. * @len: The number of bytes of uncompressed data to read from * the resource. * @offset: The offset of the bytes to read within the uncompressed * resource. * @contents_len: An array into which the uncompressed data is written. * It must be at least @len bytes long. * * Returns zero on success, nonzero on failure. */ static int read_compressed_resource(FILE *fp, u64 resource_compressed_size, u64 resource_uncompressed_size, u64 resource_offset, int resource_ctype, u64 len, u64 offset, u8 contents_ret[]) { DEBUG2("comp size = %"PRIu64", " "uncomp size = %"PRIu64", " "res offset = %"PRIu64"\n", resource_compressed_size, resource_uncompressed_size, resource_offset); DEBUG2("resource_ctype = %s, len = %"PRIu64", offset = %"PRIu64"\n", wimlib_get_compression_type_string(resource_ctype), len, offset); /* Trivial case */ if (len == 0) return 0; int (*decompress)(const void *, uint, void *, uint); /* Set the appropriate decompress function. */ if (resource_ctype == WIM_COMPRESSION_TYPE_LZX) decompress = lzx_decompress; else decompress = xpress_decompress; /* The structure of a compressed resource consists of a table of chunk * offsets followed by the chunks themselves. Each chunk consists of * compressed data, and there is one chunk for each WIM_CHUNK_SIZE = * 32768 bytes of the uncompressed file, with the last chunk having any * remaining bytes. * * The chunk offsets are measured relative to the end of the chunk * table. The first chunk is omitted from the table in the WIM file * because its offset is implicitly given by the fact that it directly * follows the chunk table and therefore must have an offset of 0. */ /* Calculate how many chunks the resource conists of in its entirety. */ u64 num_chunks = (resource_uncompressed_size + WIM_CHUNK_SIZE - 1) / WIM_CHUNK_SIZE; /* As mentioned, the first chunk has no entry in the chunk table. */ u64 num_chunk_entries = num_chunks - 1; /* The index of the chunk that the read starts at. */ u64 start_chunk = offset / WIM_CHUNK_SIZE; /* The byte offset at which the read starts, within the start chunk. */ u64 start_chunk_offset = offset % WIM_CHUNK_SIZE; /* The index of the chunk that contains the last byte of the read. */ u64 end_chunk = (offset + len - 1) / WIM_CHUNK_SIZE; /* The byte offset of the last byte of the read, within the end chunk */ u64 end_chunk_offset = (offset + len - 1) % WIM_CHUNK_SIZE; /* Number of chunks that are actually needed to read the requested part * of the file. */ u64 num_needed_chunks = end_chunk - start_chunk + 1; /* If the end chunk is not the last chunk, an extra chunk entry is * needed because we need to know the offset of the chunk after the last * chunk read to figure out the size of the last read chunk. */ if (end_chunk != num_chunks - 1) num_needed_chunks++; /* Declare the chunk table. It will only contain offsets for the chunks * that are actually needed for this read. */ u64 chunk_offsets[num_needed_chunks]; /* Set the implicit offset of the first chunk if it is included in the * needed chunks. * * Note: M$'s documentation includes a picture that shows the first * chunk starting right after the chunk entry table, labeled as offset * 0x10. However, in the actual file format, the offset is measured * from the end of the chunk entry table, so the first chunk has an * offset of 0. */ if (start_chunk == 0) chunk_offsets[0] = 0; /* According to M$'s documentation, if the uncompressed size of * the file is greater than 4 GB, the chunk entries are 8-byte * integers. Otherwise, they are 4-byte integers. */ u64 chunk_entry_size = (resource_uncompressed_size >= (u64)1 << 32) ? 8 : 4; /* Size of the full chunk table in the WIM file. */ u64 chunk_table_size = chunk_entry_size * num_chunk_entries; /* Read the needed chunk offsets from the table in the WIM file. */ /* Index, in the WIM file, of the first needed entry in the * chunk table. */ u64 start_table_idx = (start_chunk == 0) ? 0 : start_chunk - 1; /* Number of entries we need to actually read from the chunk * table (excludes the implicit first chunk). */ u64 num_needed_chunk_entries = (start_chunk == 0) ? num_needed_chunks - 1 : num_needed_chunks; /* Skip over unneeded chunk table entries. */ u64 file_offset_of_needed_chunk_entries = resource_offset + start_table_idx * chunk_entry_size; if (fseeko(fp, file_offset_of_needed_chunk_entries, SEEK_SET) != 0) { ERROR("Failed to seek to byte %"PRIu64" " "to read chunk table of compressed " "resource: %m\n", file_offset_of_needed_chunk_entries); return WIMLIB_ERR_READ; } /* Number of bytes we need to read from the chunk table. */ size_t size = num_needed_chunk_entries * chunk_entry_size; u8 chunk_tab_buf[size]; if (fread(chunk_tab_buf, 1, size, fp) != size) goto err; /* Now fill in chunk_offsets from the entries we have read in * chunk_tab_buf. */ u64 *chunk_tab_p = chunk_offsets; if (start_chunk == 0) chunk_tab_p++; if (chunk_entry_size == 4) { u32 *entries = (u32*)chunk_tab_buf; while (num_needed_chunk_entries--) *chunk_tab_p++ = to_le32(*entries++); } else { u64 *entries = (u64*)chunk_tab_buf; while (num_needed_chunk_entries--) *chunk_tab_p++ = to_le64(*entries++); } /* Done with the chunk table now. We must now seek to the first chunk * that is needed for the read. */ u64 file_offset_of_first_needed_chunk = resource_offset + chunk_table_size + chunk_offsets[0]; if (fseeko(fp, file_offset_of_first_needed_chunk, SEEK_SET) != 0) { ERROR("Failed to seek to byte %"PRIu64" " "to read first chunk of compressed " "resource: %m\n", file_offset_of_first_needed_chunk); return WIMLIB_ERR_READ; } /* Pointer to current position in the output buffer for uncompressed * data. */ u8 *out_p = (u8*)contents_ret; /* Buffer for compressed data. While most compressed chunks will have a * size much less than WIM_CHUNK_SIZE, WIM_CHUNK_SIZE - 1 is the maximum * size in the worst-case. This assumption is valid only if chunks that * happen to compress to more than the uncompressed size (i.e. a * sequence of random bytes) are always stored uncompressed. But this seems * to be the case in M$'s WIM files, even though it is undocumented. */ u8 compressed_buf[WIM_CHUNK_SIZE - 1]; /* Decompress all the chunks. */ for (u64 i = start_chunk; i <= end_chunk; i++) { DEBUG2("Chunk %"PRIu64" (start %"PRIu64", end %"PRIu64")\n", i, start_chunk, end_chunk); /* Calculate the sizes of the compressed chunk and of the * uncompressed chunk. */ uint compressed_chunk_size, uncompressed_chunk_size; if (i != num_chunks - 1) { /* All the chunks except the last one in the resource * expand to WIM_CHUNK_SIZE uncompressed, and the amount * of compressed data for the chunk is given by the * difference of offsets in the chunk offset table. */ compressed_chunk_size = chunk_offsets[i + 1 - start_chunk] - chunk_offsets[i - start_chunk]; uncompressed_chunk_size = WIM_CHUNK_SIZE; } else { /* The last compressed chunk consists of the remaining * bytes in the file resource, and the last uncompressed * chunk has size equal to however many bytes are left- * that is, the remainder of the uncompressed size when * divided by WIM_CHUNK_SIZE. * * Note that the resource_compressed_size includes the * chunk table, so the size of it must be subtracted. */ compressed_chunk_size = resource_compressed_size - chunk_table_size - chunk_offsets[i - start_chunk]; uncompressed_chunk_size = resource_uncompressed_size % WIM_CHUNK_SIZE; /* If the remainder is 0, the last chunk actually * uncompresses to a full WIM_CHUNK_SIZE bytes. */ if (uncompressed_chunk_size == 0) uncompressed_chunk_size = WIM_CHUNK_SIZE; } DEBUG2("compressed_chunk_size = %u, uncompressed_chunk_size = %u\n", compressed_chunk_size, uncompressed_chunk_size); /* Figure out how much of this chunk we actually need to read */ u64 start_offset; if (i == start_chunk) start_offset = start_chunk_offset; else start_offset = 0; u64 end_offset; if (i == end_chunk) end_offset = end_chunk_offset; else end_offset = WIM_CHUNK_SIZE - 1; u64 partial_chunk_size = end_offset + 1 - start_offset; bool is_partial_chunk = (partial_chunk_size != uncompressed_chunk_size); DEBUG2("start_offset = %u, end_offset = %u\n", start_offset, end_offset); DEBUG2("partial_chunk_size = %u\n", partial_chunk_size); /* This is undocumented, but chunks can be uncompressed. This * appears to always be the case when the compressed chunk size * is equal to the uncompressed chunk size. */ if (compressed_chunk_size == uncompressed_chunk_size) { /* Probably an uncompressed chunk */ if (start_offset != 0) { if (fseeko(fp, start_offset, SEEK_CUR) != 0) { ERROR("Uncompressed partial chunk " "fseek() error: %m\n"); return WIMLIB_ERR_READ; } } if (fread(out_p, 1, partial_chunk_size, fp) != partial_chunk_size) goto err; } else { /* Compressed chunk */ int ret; /* Read the compressed data into compressed_buf. */ if (fread(compressed_buf, 1, compressed_chunk_size, fp) != compressed_chunk_size) goto err; /* For partial chunks we must buffer the uncompressed * data because we don't need all of it. */ if (is_partial_chunk) { u8 uncompressed_buf[uncompressed_chunk_size]; ret = decompress(compressed_buf, compressed_chunk_size, uncompressed_buf, uncompressed_chunk_size); if (ret != 0) return WIMLIB_ERR_DECOMPRESSION; memcpy(out_p, uncompressed_buf + start_offset, partial_chunk_size); } else { DEBUG2("out_p = %p\n"); ret = decompress(compressed_buf, compressed_chunk_size, out_p, uncompressed_chunk_size); if (ret != 0) return WIMLIB_ERR_DECOMPRESSION; } } /* Advance the pointer into the uncompressed output data by the * number of uncompressed bytes that were written. */ out_p += partial_chunk_size; } return 0; err: if (feof(fp)) ERROR("Unexpected EOF in compressed file resource\n"); else ERROR("Error reading compressed file resource: %m\n"); return WIMLIB_ERR_READ; } /* * Reads uncompressed data from an open file stream. */ int read_uncompressed_resource(FILE *fp, u64 offset, u64 len, u8 contents_ret[]) { if (fseeko(fp, offset, SEEK_SET) != 0) { ERROR("Failed to seek to byte %"PRIu64" of input file " "to read uncompressed resource " "(len = %"PRIu64")!\n", offset, len); return WIMLIB_ERR_READ; } if (fread(contents_ret, 1, len, fp) != len) { if (feof(fp)) { ERROR("Unexpected EOF in uncompressed file resource!\n"); } else { ERROR("Failed to read %"PRIu64" bytes from " "uncompressed resource at offset " "%"PRIu64"\n", len, offset); } return WIMLIB_ERR_READ; } return 0; } /* * Reads a WIM resource. * * @fp: The FILE* for the WIM file. * @resource_size: The compressed size of the resource. * @resource_original_size: The uncompressed size of the resource. * @resource_offset: The offset of the resource in the stream @fp. * @resource_ctype: The compression type of the resource. * (WIM_COMPRESSION_TYPE_*) * @len: How many bytes of the resource should be read. * @offset: The offset within the resource at which the read * will occur. * * To read the whole file resource, specify offset = * 0 and len = resource_original_size, or call * read_full_resource(). * * @contents_ret: An array, that must have length at least @len, * into which the uncompressed contents of * the file resource starting at @offset and * continuing for @len bytes will be written. * * @return: Zero on success, nonzero on failure. Failure may be due to * being unable to read the data from the WIM file at the * specified length and offset, or it may be due to the * compressed data (if the data is compressed) being * invalid. */ int read_resource(FILE *fp, u64 resource_size, u64 resource_original_size, u64 resource_offset, int resource_ctype, u64 len, u64 offset, void *contents_ret) { if (resource_ctype == WIM_COMPRESSION_TYPE_NONE) { if (resource_size != resource_original_size) { ERROR("Resource with original size %"PRIu64" " "bytes is marked as uncompressed, \n", resource_original_size); ERROR(" but its actual size is %"PRIu64" " "bytes!\n", resource_size); return WIMLIB_ERR_INVALID_RESOURCE_SIZE; } return read_uncompressed_resource(fp, resource_offset + offset, len, contents_ret); } else { return read_compressed_resource(fp, resource_size, resource_original_size, resource_offset, resource_ctype, len, offset, contents_ret); } } /* * Extracts the first @size bytes file resource specified by @entry to the open * file @fd. Returns nonzero on error. * * XXX * This function is somewhat redundant with uncompress_resource(). The * main difference is that this function writes to a file descriptor using * low-level calls to write() rather than to a FILE* with fwrite(); also this * function allows only up to @size bytes to be extracted. */ int extract_resource_to_fd(WIMStruct *w, const struct resource_entry *entry, int fd, u64 size) { u64 num_chunks; u64 n; u8 buf[min(size, WIM_CHUNK_SIZE)]; int res_ctype; u64 offset; u64 i; int ret; errno = 0; num_chunks = (size + WIM_CHUNK_SIZE - 1) / WIM_CHUNK_SIZE; n = WIM_CHUNK_SIZE; res_ctype = wim_resource_compression_type(w, entry); offset = 0; for (i = 0; i < num_chunks; i++) { if (i == num_chunks - 1) { n = size % WIM_CHUNK_SIZE; if (n == 0) { n = WIM_CHUNK_SIZE; } } ret = read_resource(w->fp, entry->size, entry->original_size, entry->offset, res_ctype, n, offset, buf); if (ret != 0) return ret; if (full_write(fd, buf, n) != n) return WIMLIB_ERR_WRITE; offset += n; } return ret; } /* Reads the contents of a struct resource_entry, as represented in the on-disk * format, from the memory pointed to by @p, and fills in the fields of @entry. * A pointer to the byte after the memory read at @p is returned. */ const u8 *get_resource_entry(const u8 *p, struct resource_entry *entry) { u64 size; u8 flags; p = get_u56(p, &size); p = get_u8(p, &flags); entry->size = size; entry->flags = flags; p = get_u64(p, &entry->offset); p = get_u64(p, &entry->original_size); return p; } /* Copies the struct resource_entry @entry to the memory pointed to by @p in the * on-disk format. A pointer to the byte after the memory written at @p is * returned. */ u8 *put_resource_entry(u8 *p, const struct resource_entry *entry) { p = put_u56(p, entry->size); p = put_u8(p, entry->flags); p = put_u64(p, entry->offset); p = put_u64(p, entry->original_size); return p; } /* Given the compression type for the WIM file as a whole as the flags field of * a resource entry, returns the compression type for that resource entry. */ int resource_compression_type(int wim_ctype, int reshdr_flags) { if (wim_ctype == WIM_COMPRESSION_TYPE_NONE) { return WIM_COMPRESSION_TYPE_NONE; } else { if (reshdr_flags & WIM_RESHDR_FLAG_COMPRESSED) return wim_ctype; else return WIM_COMPRESSION_TYPE_NONE; } } /* * Reads the metadata metadata resource from the WIM file. The metadata * resource consists of the security data, followed by the directory entry for * the root directory, followed by all the other directory entries in the * filesystem. The subdir_offset field of each directory entry gives the start * of its child entries from the beginning of the metadata resource. An * end-of-directory is signaled by a directory entry of length '0', really of * length 8, because that's how long the 'length' field is. * * @fp: The FILE* for the input WIM file. * @res_entry: The resource entry for the metadata resource (a.k.a the metadata * for the metadata) * @wim_ctype: The compression type of the WIM file. * @root_dentry_p: A pointer to a pointer to a struct dentry structure into which the * root dentry is allocated and returned. * * @return: True on success, false on failure. */ int read_metadata_resource(FILE *fp, const struct resource_entry *res_entry, int wim_ctype, struct dentry **root_dentry_p) { u8 *buf; int ctype; u32 dentry_offset; int ret; struct dentry *dentry; DEBUG("Reading metadata resource: length = %lu, offset = %lu\n", res_entry->original_size, res_entry->offset); if (res_entry->original_size < 8) { ERROR("Expected at least 8 bytes for the metadata " "resource!\n"); return WIMLIB_ERR_INVALID_RESOURCE_SIZE; } /* Allocate memory for the uncompressed metadata resource. */ buf = MALLOC(res_entry->original_size); if (!buf) { ERROR("Failed to allocate %"PRIu64" bytes for uncompressed " "metadata resource!\n", res_entry->original_size); return WIMLIB_ERR_NOMEM; } /* Determine the compression type of the metadata resource. */ ctype = resource_compression_type(wim_ctype, res_entry->flags); /* Read the metadata resource into memory. (It may be compressed.) */ ret = read_full_resource(fp, res_entry->size, res_entry->original_size, res_entry->offset, ctype, buf); if (ret != 0) goto err1; DEBUG("Finished reading metadata resource into memory.\n"); #if 0 /* Read the security data into a WIMSecurityData structure. */ if (!read_security_data(buf, res_entry->original_size, sd)) goto err1; #endif dentry = MALLOC(sizeof(struct dentry)); if (!dentry) { ERROR("Failed to allocate %zu bytes for root dentry!\n", sizeof(struct dentry)); ret = WIMLIB_ERR_NOMEM; goto err1; } /* Read the root directory entry starts after security data, on an * 8-byte aligned address. * * The security data starts with a 4-byte integer giving its total * length. */ get_u32(buf, &dentry_offset); dentry_offset += (8 - dentry_offset % 8) % 8; ret = read_dentry(buf, res_entry->original_size, dentry_offset, dentry); if (ret != 0) goto err1; /* This is the root dentry, so set its pointers correctly. */ dentry->parent = dentry; dentry->next = dentry; dentry->prev = dentry; /* Now read the entire directory entry tree. */ ret = read_dentry_tree(buf, res_entry->original_size, dentry); if (ret != 0) goto err2; /* Calculate the full paths in the dentry tree. */ ret = for_dentry_in_tree(dentry, calculate_dentry_full_path, NULL); if (ret != 0) goto err2; *root_dentry_p = dentry; FREE(buf); return ret; err2: free_dentry_tree(dentry, NULL, false); err1: FREE(buf); return ret; }